The present invention relates to a data reproducing device suitable for a data recorder based on a format such as the ID-1 format.
In a conventional video tape recorder (VTR) for recording and reproducing video signals by helically scanning a magnetic tape with a rotary head, there are a plurality of recording tracks in the longitudinal direction of the magnetic tape in addition to video tracks consisting of helical recording tracks. Voice signals, control signals and time codes are recorded on these longitudinal tracks and also reproduced therefrom.
In such a VTR, control signals, pulse signals or the like corresponding to video tracks positions are recorded. These control signals are regenerated, and scan timings or the like of the rotary head and a traveling system of the magnetic tape are servo-controlled.
Absolute time information of the video tracks is recorded as a time code. The position of a desired video track is recorded to permit accurate editing and seeking of the regenerative top.
If the time codes are not correctly regenerated due to drop-out or the like, time codes are corrected corresponding to the timings of the simultaneous control signals. This prevents errors in the editing or the seeking of regenerative top.
In the proposed ID-1 format, (Third Draft PROPOSED AMERICAN NATIONAL STANDARD 19 mm TYPE ID-1 INSTRUMENTATION DIGITAL CASSETTE FORMAT X3B6/88-12 Project 592-D 1988-03-22) desired information data is recorded and reproduced from the magnetic tape by utilizing the SMPTE D-1 digital VTR format.
In the ID-1 format, as illustrated in FIG. 1(A), the desired information data are recorded on and reproduced from the helical recording tracks serving as data tracks TR on a magnetic tape TP. Formed at the lower ends of the data tracks TR are a control signal track CTL and a time code track TC in the longitudinal direction of the magnetic tape TP.
The time code track TC is available for the user. Recorded on the control signal track CTL is, as illustrated in FIG. 1(B), synchronous data segments SYNC consisting of 4 bits and indicating a section T1-T2 of four helical data tracks TR0, TR1, TR2 and TR3 with located between second bits and third bits thereof. 28-bit identification data segments are recorded between the synchronous data SYNC.
In the 28-bit identification data, track set identification data TSID numbered from the top according to the four data tracks TR0, TR1, TR2, TR3 are recorded in 23 bits following the synchronous data SYNC; a home track identification data HTID representing recording head information or the like are recorded in the subsequent 4 bits; and a 1-bit even-numbered parity PR is appended thereto.
Hence, in the ID-1 format data recorder, as in the control signals of a VTR, scan timings of the rotary head and the traveling system of the magnetic tape TP can be servo-controlled by reproducing the synchronous data SYNC recorded on the control signal track CTL. Identification data TSID, HTID, PR recorded on the control signal track CTL are reproduced, thereby detecting positions of data tracks TR0, TR1, TR2, TR3 in the same manner as with time codes in a VTR. It is therefore possible to accurately execute editing and seeking of the regenerative top.
In the data recorder based on the above-described ID-1 format, however, the same functions as those of the control signal and the time code in VTR are actualized only by the recording information on the control signal track CTL. Hence, if the drop-out or the like takes place, there is a possibility that the identification data TSID, HTID, PR cannot be reproduced.
If the identification data TSID, HTID, PR on the control signal track CTL cannot be correctly reproduced, there is an increased possibility that the synchronous data SYNC on the control signal track CTL cannot be also correctly reproduced. For this reason, the correction cannot be effected by use of timings of the synchronous data SYNC as in the case of a VTR where identification data TSID, HTID, PR cannot be reproduced.
To obviate such a problem, there can be recorded on the data tracks TR0, TR1, TR2, TR3 of the magnetic tape TP, the same time codes as the vertical interval time codes (VITC) of a VTR which are recorded on the video tracks while being overlapped with a vertical synchronous period of the video signal.
With this arrangement, even when the identification data TSID, HTID, PR on the control signal track CTL cannot be correctly reproduced, the correction can be made at the timings based on the time codes recorded on the data tracks TR0, TR1, TR2, TR3.
If the same time codes as those of VITC are recorded on and reproduced from the data tracks TR0, TR1, TR2, TR3, however, a circuit for recording and reproducing the time codes is required and reproducing the time codes is required in the processing circuit for recording and reproducing the information data. A problem arises in that the circuitry inevitably becomes complicated and correspondingly large in size.